Patent GB-1311020-A (GB)
Title: Power transmission
IPC: F16H61/02
Filed: 1970-12-29
Abstract: 1311020 Change-speed gear NISSAN MOTOR CO Ltd 29 Dec 1970 [29 Dec 1969 6 Feb 1970] 61624/70 Heading F2D A constant mesh three-speeds and reverse dog-clutched countershaft gear, driven through a tongue-converter 15 and fluid-operated separating clutch 17, on a motor-vehicle includes a one-way clutch 26 in its first-ratio clutch dog 20a, so that second and third ratios can be established without the need to disconnect I-R clutch-dog 23 from its first-ratio setting. The I-R clutch dog 23 is operated by mechanical linkage from a PRND II I lever 26, the 2-3 dog 22 being operated by a threeposition fluid servomotor 35. During shift, the separating clutch 17 is released and the engine throttle closed. An automatic electronic shift control responds to output speed, engine throttle setting, service brakes, engine temperature and road gradient, the last three acting to raise the speed of the shift points. Third ratio is temporarily established at low-throttle standstill for anti-creep. Manual control may replace the automatic. Mechanical selection of the I-R clutch dog 22. The manual ranging lever 36 turns about a fixed pivot 40 to move a pin 41, rigid with the lever 36, along a cam slot in a cam plate 38, which turns a rockshaft 31 actuating the 1-R clutch dog 22. The cam slot is in three sections, of which only the centre section produces movement of the cam plate 38, the outer sections being arcuate with offset centres coinciding with the shift-lever pivot 40 when the cam plate is moved in either direction from neutral. Thus, in moving from N to R the clutch-dog 22 is moved to engage the reverse wheel 21, and remains engaged therewith during subsequent movement of the shift lever 36 in the same direction to P, where a park lock pawl 49 is applied through a link 47; whilst in moving from N to D, the dog 22 is engaged with the one-way first-ratio wheel 20, and held there during any subsequent movement in the same direction to II or I. Fluid servo circuit. The three-position servo 35 for shifting the 2-3 clutch dog 22 comprises two relatively-slidable pistons 56, 57, Fig. 3, in a stepped cylinder with end supply ports 54, 55, which, when pressurized together, establish neutral (shown), and pressurized separately direct both pistons to the right for third ratio, or the piston 56 alone to the left for second, the clutch-dog 22 being actuated through a lever 29, Fig. 1, freely pivoted on the 1-2 rockshaft 31. The second ratio port 54 is pressurized by energizing a solenoid 69a to blank a restricted exhaust from a chamber 107, permitting regulated and restricted main pressure 64 to shift a valve 69 to the right, supplying main pressure 64, 66 to the second ratio servo port 54. The third ratio port 55 is pressurized by deenergizing a solenoid 70a, opening a restricted exhaust to a chamber 121 to permit a spring to shift a valve 70 to the left, to supply main pressure 64, 67 to the third-ratio port 55. Thus 2-3 neutral requires the solenoid 69a to be energized, and 70a de-energized; second ratio both solenoids energized; and third ratio both de-energized. The separating clutch 17 is engaged by main pressure 62, 65, fed through a clutch-valve 68, line 81 and an engine-intake-modulated regulator valve 87. Energizing a solenoid 68a blanks the restricted exhaust from a chamber 84; permitting main pressure 65 to shift the clutch-valve 68 right, exhausting the apply line 81 and pressurizing a clutch-release line 80. Electronic circuit, Figs. 6a, 6b. The shift solenoids 69a, 70a, and separating clutch release solenoid 68a, together with an engine-throttle closer 189 (not described) are controlled by the first, second and third ratio outputs 166, 167, 168 of a shift pattern generator 130 (not described) which responds to signals representing engine-throttle setting 135, output speed 136, service brake application 132, engine temperature 133 and road grade 134, the last three serving to raise all the shift-speeds above those for level road conditions. The shiftpatterns (Figs. 4 and 5, not shown) provide updown hysteresis and that for level road (Fig. 4, not shown) provides that, with the vehicle stationary and throttle opening below 10%, third gear is established to produce maximum creep resistance, first gear being engaged on accelerator depression. Shift action.-A selector switch 131, actuated by the manual shift lever 26, energizes the engine start circuit 152 in N, a reverse lamp in R, and a line 153 in D. On entering D setting, in the absence of signals from brake, engine thermometer, and road grade 132, 133, 134, the shift pattern generator 130 generates the 168 signal, de-energizing both solenoids 69a, 70a for establishing third ratio for anti-creep. Depression of the accelerator changes the signal to 166, energizing the solenoid 69a only for 2-3 neutral, so that the vehicle starts in the mechanically, selected oneway first ratio. Speed and throttle signals 165, 164 cause the shift pattern generator 130 to extinguish signal 166 and produce a signal in line 167, which energizes both solenoids 69a, 70a for second ratio, followed by a third ratio signal 168, de-energizing both solenoids. Manual II and I settings send the same signal 156 to the shift pattern generator 130, which produces the first ratio signal 166, energizing the solenoid 69a. In I setting this is the only solenoid energized, producing 2-3 neutral and hence first ratio. In II setting an additional signal is applied from the selector switch 131 to a line 158, which, together with the first ratio 166 signal, causes a first AND circuit 159 to issue a signal 178, energizing the second solenoid 70a as well as the first, giving second ratio. Emergency selection.-If the electronic system fails, first and third ratios can be manually selected as follows. An emergency switch 144 is operated to energize a line 148, which, in an E setting of the selector switch. 131, energizes the first solenoid 69a through a line 160, to establish 2-3 neutral and hence first ratio. In other than E position, neither solenoid 69a or 70a is energized providing third ratio. An additional manual shift lever may be provided for direct mechanical operation of the 2-3 clutch 22. Separating clutch action.-Two separate circuits, one for the automatic shifts, the other for manual, control the release solenoid 68a of the separating clutch 17, together with the enginethrottle closer 189 (not described). For manual shifts or movement into R or D, the clutch release solenoid 68a is energized by grasping the shift lever 26 to close a switch 197 feeding a line 199. For automatic shifts, the first second and third ratio signal lines 166, 167 and 168 from the shift pattern generator 130, signal first second and third differentiating circuits 170, 181, 195 respectively, feeding, through a second OR circuit 172, a timer circuit 174, the output 200 of which is applied as a square-wave pulse to the clutch-release solenoid 68a and throttle closer 189. To ensure that the release solenoid 68a is maintained energized until 2-3 shift is completed, the second and third shift signals 167, 168 feed the clutch-release line 190 through second and third AND circuits 185, 192, and a fourth OR circuit, being effective only when receiving a signal from a shift-rod switch 201 which opens when the 2-3 shift rod has completed its movement to erase the release signal 188.